ROMJIST Volume 29, No. 2, 2026, pp. 201-210, DOI: 10.59277/ROMJIST.2026.2.09
Iulia ANTOHE, Gianina POPESCU-PELIN, Gabriel SOCOL, Luiza-Izabela TODERASCU, Cristian ZAGAR Plasmonic Optical Fiber-based Sensor for Monitoring Toxic Nitrophenolic Compounds
ABSTRACT: The detection of nitrophenolic compounds, including 4-nitrophenol (4-NP) and 2,4-dinitrophenol (2,4-DNP), is essential because of their significant environmental persistence and toxic effects on living organisms. In this work, we present a sensitive and selective approach based on a polyaniline (PANI)-coated fiber optic-surface plasmon resonance (FOSPR) sensor for real-time monitoring of these pollutants in aqueous environments. The PANI layer was fabricated directly onto the gold-coated sensing region of an unclad optical fiber via chemical oxidative polymerization, ensuring uniform coverage and strong adhesion. The PANI layer was characterized using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), which provided detailed information on its morphological features and chemical composition. Moreover, the sensor performance was evaluated by tracking the shifts in the SPR wavelength upon analyte interaction. The developed sensor exhibited a clear linear response to both target compounds, achieving detection limits of 33 nM for 4-NP and 14 nM for 2,4-DNP. Moreover, the proposed FO-SPR sensor offers key advantages, including low cost, label-free operation, and rapid response, making it highly suitable for continuous environmental monitoring. Overall, this FO-SPR sensing technology represents a promising and practical solution for detecting hazardous nitrophenolic contaminants in water systems.KEYWORDS: Chemical polymerization; fiber optic plasmonic sensor; nitrophenolic compounds; polyaniline.Read full text (pdf)